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authorDavid S. Miller <davem@davemloft.net>2014-04-11 16:15:36 -0400
committerDavid S. Miller <davem@davemloft.net>2014-04-11 16:15:36 -0400
commit676d23690fb62b5d51ba5d659935e9f7d9da9f8e (patch)
treef6fbceee43e05c724868153ca37b702fb5e43b8c /net/sctp
parentad20d5f673898578f9d8a156d7a4c921f5ca4584 (diff)
net: Fix use after free by removing length arg from sk_data_ready callbacks.
Several spots in the kernel perform a sequence like: skb_queue_tail(&sk->s_receive_queue, skb); sk->sk_data_ready(sk, skb->len); But at the moment we place the SKB onto the socket receive queue it can be consumed and freed up. So this skb->len access is potentially to freed up memory. Furthermore, the skb->len can be modified by the consumer so it is possible that the value isn't accurate. And finally, no actual implementation of this callback actually uses the length argument. And since nobody actually cared about it's value, lots of call sites pass arbitrary values in such as '0' and even '1'. So just remove the length argument from the callback, that way there is no confusion whatsoever and all of these use-after-free cases get fixed as a side effect. Based upon a patch by Eric Dumazet and his suggestion to audit this issue tree-wide. Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sctp')
-rw-r--r--net/sctp/socket.c2
-rw-r--r--net/sctp/ulpqueue.c4
2 files changed, 3 insertions, 3 deletions
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 270d5bd97d8b..e13519e9df80 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -6745,7 +6745,7 @@ do_nonblock:
6745 goto out; 6745 goto out;
6746} 6746}
6747 6747
6748void sctp_data_ready(struct sock *sk, int len) 6748void sctp_data_ready(struct sock *sk)
6749{ 6749{
6750 struct socket_wq *wq; 6750 struct socket_wq *wq;
6751 6751
diff --git a/net/sctp/ulpqueue.c b/net/sctp/ulpqueue.c
index 5dc94117e9d4..7144eb6a1b95 100644
--- a/net/sctp/ulpqueue.c
+++ b/net/sctp/ulpqueue.c
@@ -259,7 +259,7 @@ int sctp_ulpq_tail_event(struct sctp_ulpq *ulpq, struct sctp_ulpevent *event)
259 sctp_ulpq_clear_pd(ulpq); 259 sctp_ulpq_clear_pd(ulpq);
260 260
261 if (queue == &sk->sk_receive_queue) 261 if (queue == &sk->sk_receive_queue)
262 sk->sk_data_ready(sk, 0); 262 sk->sk_data_ready(sk);
263 return 1; 263 return 1;
264 264
265out_free: 265out_free:
@@ -1135,5 +1135,5 @@ void sctp_ulpq_abort_pd(struct sctp_ulpq *ulpq, gfp_t gfp)
1135 1135
1136 /* If there is data waiting, send it up the socket now. */ 1136 /* If there is data waiting, send it up the socket now. */
1137 if (sctp_ulpq_clear_pd(ulpq) || ev) 1137 if (sctp_ulpq_clear_pd(ulpq) || ev)
1138 sk->sk_data_ready(sk, 0); 1138 sk->sk_data_ready(sk);
1139} 1139}